1. Field of the Invention
Implementations of various technologies described herein generally relate to methods and systems for processing seismic data for a towed marine survey.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Seismic data signals are typically acquired by measuring and recording data during a land or marine seismic survey. A land seismic survey may be performed by repeatedly firing an impulsive seismic energy source at the surface of the earth and recording the received signals at a set of sensors. Similarly, a marine seismic survey may be performed by repeatedly firing an impulsive seismic energy source (e.g., air-guns, dynamite, marine vibrators or the like) into the sea or at the seafloor and recording the received signals at a set of sensors. In a towed marine seismic survey, the sensors are typically disposed on seismic streamers and the source is disposed on a seismic source array. Both, the seismic streamers and the seismic source array, may be towed across the sea by a vessel. The sensors may typically be laterally displaced at regular intervals along the seismic streamers. However, there may be situations where a non-regular distribution of the sensors may be preferred or where the source array and the streamers may be positioned at different depth levels. In a typical marine seismic survey, the source and the sensors may be displaced at fixed intervals (e.g., 25 meters) and in a certain direction (e.g., the “inline” direction).
During the marine seismic survey, the cycle of firing the source and recording the received signals may be repeated a plurality of times. When firing the seismic source, a pressure wave may be excited and propagated into the subsurface of the seafloor. The pressure wave reflects off interfaces between various earth layers (such as rock, sand, shale, and chalk layers) and propagates upwardly to the set of sensors, where the particle velocity of the wave vibrations or the pressure oscillations of the wave may be measured and recorded. The measured particle velocity of the wave vibrations or the pressure oscillations of the wave may then be used to generate a seismic image of the subterranean surface of the seafloor.